Introductory Physics 1 - Test 3 (Impulse & Momentum)

(2 kg × 4 m/s) + 4v = (2 kg + 4 m/s)(0) 8 + 4v = 0 v = 2 m/s

A 2 kg cart rolling to the right at 4 m/s runs into a 4 kg cart rolling to the left. After the collision, both carts are stationary. What was the original speed of the 4 kg cart?

Initial momentum of boxcar = Mass × Velocity = 14000 × 1.5 = 21000 kg*m/s Final mass of car = 14000 kg + 10000 kg = 24000 kg Final momentum = Initial momentum 24000 kg × v = 21000 kg*m/s v = 0.875 m/s

Conservation of Momentum: A 14,000-kg boxcar is coasting at 1.50 m/s along a horizontal track when it suddenly hits and couples with a stationary 10,000-kg boxcar. What is the speed of the cars just after the collision?

(328 kg × 19.1 m/s) + (790 kg × 13.0 m/s) - (790 kg × 15.1 m/s) / 328 kg V1 = 14.04 m/s

Conservation of Momentum: A 328-kg car moving at 19.1 m/s in the +x direction hits from behind a second car moving at 13.0 m/s in the same direction. If the second car has a mass of 790 kg and a speed of 15.1 m/s right after the collision, what is the velocity of the first car after this sudden collision?

(60 kg)(1.5 m/s) = (150 kg)(V) V = 0.6 m/s

Conservation of Momentum: A 60-kg swimmer suddenly dives horizontally from a 150-kg raft with a speed of 1.5 m/s. The raft is initially at rest. What is the speed of the raft immediately after the diver jumps if the water has negligible effect on the raft?

2 kg × 20 m/s = 40 kg*m/s 40 kg*m/s / 200 kg = 0.2 100 m / 0.2 = 500 s

Conservation of Momentum: Astronaut Jennifer's lifeline to her spaceship comes loose and she finds herself stranded, "floating" 100 m from the mothership. She suddenly throws her 2.00-kg wrench at 20 m/s in a direction away from the ship. If she and her spacesuit have a combined mass of 200 kg, how long does it take her to coast back to her spaceship?

0.002 × 700 + 0 × 5 = (0.002 + 5) × V V = 0.28 m/s

Conservation of Momentum: In a police ballistics test, 2.00-g bullet traveling at 700 m/s suddenly hits and becomes embedded in a stationary 5.00-kg wood block. What is the speed of the block immediately after the bullet has stopped moving relative to the block?

in both elastic and inelastic collisions.

Conservation of Momentum: The momentum of an isolated system is conserved...

Impulse = 8000 × 1.1 × 10⁻³ = 8.8 N*s

Impulse: A batter applies an average force of 8000 N to a baseball for 1.1 m/s. What is the magnitude of the impulse delivered to the baseball by the bat?

F(avg) × t = m(v2 - v1) F(avg) = m(v2 - v1)/t = 0.14(40 - (-30)) / 2 × 10⁻³ = 4900 N

Impulse: A batter hits a 0.140-kg baseball that was approaching him at 30 m/s and, as a result, the ball leaves the bat at 40 m/s in the reverse of its original direction. The ball remains in contact with the bat for 2.0 ms. What is the magnitude of the average force exerted by the bat on the ball?

F × t = M(v - u) F × 0.2 = 5.6 × (6.5 - (-0.7)) = 201.6 N

Impulse: A block of mass m = 5.6 kg, moving on a frictionless surface with a velocity of vi = 6.5 m/s to the right, collides with a block of mass M at rest, as shown in the figure. After the collision, the 5.6-kg block recoils with a velocity of vf = 0.70 m/s to the left. If the blocks are in contact for 0.20 s, what is the magnitude of the average force on the 5.6-kg block, while the two blocks are in contact?

F = mv/t F = (0.050 kg)(102 m/s) / 0.81 ms × 10⁻³ = 6.3 kN

Impulse: A golf ball of mass 0.050 kg is at rest on the tee. Just after being struck, it has a velocity of 102 m/s. If the club and ball were in contact for 0.81 ms, what is the average force exerted on the ball by the club?

exactly equal to the magnitude of the change in momentum of the larger mass.

Impulse: Identical forces act for the same length of time on two different objects. The magnitude of the change in momentum of the lighter object is...

momentum is conserved

In an inelastic collision,

0.14 kg × (-1.2 m/s) = -0.168 kg*m/s 0.14 - (-0.168) = 0.308 kg*m/s upwards

Momentum: A 0.140-kg baseball is dropped and reaches a speed of 1.20 m/s just before it hits the ground and bounces. It rebounds with an upward velocity of 1.00 m/s. What is the change of the ball's momentum during the bounce?

if no external forces act on the system

The total momentum of a system is conserved __________.